Encapsulated electromagnetic actuator with the armature thereof being completely enclosed



Dec. 29, 1970 HAUG 3,551,852

ENCAPSULATED ELECTROMAGNETIC ACTUATOR WITH THF ARMATURE THEREOF BEING COMPLETELY ENCLOSED Filed Aug. 12, 1968 13 INVENTOR.

United States Patent Int. 01. Hlllf 7/08 E US; Cl. 335-260 Claims ABSTRACT OF THE DISCLOSURE Actuating magnet has a magnet core surrounded by an excitation coil, and a housing formed of synthetic material, the magnet core and excitation coil being embedded in the housing.

My invention relates to actuating magnets of the electrical type and more particularly to alternating current electromagnets having laminated cores or yokes.

In conventional actuating magnets of this general type, the individual components such as for example the laminated magnet core, the excitation coil mounted thereon, the armature extending into the excitation coil, the electrical terminals for the excitation coil and the like, are always installed in separate prefabricated housings, of metal for example, mostly consisting of two parts. It is thus known, for example, to provide a bipartite metal housing which, after the installation or insertion therein of the aforementioned individual components can then be joined together with screws, and to secure the excitation coil, without a coil form in the housing, by means of molding resin. It has also been known to secure other components of the magnet in these separate prefabricated housing halves with molding resin or other suitable synthetic material. The manufacture of such known magnet constructions is relatively expensive because the assembly of the components and the mounting or fastening thereof in the housing halves is relatively complicated and requires a great number of production steps and manipulations.

It is accordingly an object of my invention to provide an actuating magnet of the aforementioned type which is capable of being very simply and inexpensively manufactured in mass production, possibly in a single operation and with a single tool.

With the foregoing and other objects in view, I provide an actuating magnet, especially an alternating current electromagnet, having a core or yoke which may be laminated, and an excitation coil, both the core and the coil being embedded in a housing formed of synthetic material.

In accordance with further features of my invention, required attachments or auxiliary elements of the magnet such as the coil connectors or junctions and the mechanical fastening elements as well as the leads for the armature and the actuating plunger, and a stroke adjustment element are all embedded directly together in the housing of synthetic plastic material or mounted or formed thereon.

In accordance with another feature of the invention, the housing of synthetic material is made pressure-tight advantageously in the vicinity of the displaceable armature so that a closed armature chamber is formed which is filled with a suitable liquid acting simultaneously as mechanical damping for the armature.

In accordance with additional features of my invention,

many types of known synthetic materials are suitable as material for the housing, which can be produced therefrom by injection molding, casting or extrusion. For this reason, a synthetic mateerial is preferably employed which can be processed very well by injection molding and has high temperature resistance or stability, good electrical insulating properties and mechanical sliding features as well as a high resistance, with adequate damping properties, to mechanical impacts and good thermal conductivity. These properties are characteristic above all for polyamides with or without reinforcement by glass fibers or the like. For casting purposes, either epoxy resin or ethoxyline resin is best suited.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in actuating magnet, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and 'within the scope and range of equivalents of the claims.

The construction of the invention, however, together with the additional objects and advantages thereof will be best understood from the following description when read in connection with the accompanying drawings, in which:

FIG. 1 is a bottom plan view of an alternating current electromagnet constructed in accordance with my invention;

FIG. 2 is a front elevational view, partly in section, of FIG. 1;

FIG. 3 is a side elevational view, partly in section, of FIGS. 1 and 2; and

FIG. 4 is a top plan view, partly in section, of FIGS. 1 to 3.

Referring now to the figures of the drawing, there is shown an alternating current electromagnet having a substantially U-shaped core or yoke 1 of laminate plates of iron, for example, as well as an excitation coil 3 surrounding the core 1. A substantially T-shaped armature 2, also of laminate plates, is displaceably inserted in the excitation coil 3. The core 1 and the coil 3 are embedded in a housing 4 formed of synthetic plastic material. At the upper part of the housing 4, as shown in FIG. 3, there is formed an armature chamber 10 surrounding the upper end of the armature 2.

The armature chamber 10 is closed by a housing cover 11. In the illustrated embodiment of the drawing, the upper rim of the housing 4, as viewed in FIG. 3 for example, is provided with an inner thread into which the externally threaded housing cover 11 is screwed. By screwing the housing cover 11 a greater or lesser distance into the inner thread formed in the housing 4, the length of stroke of the armature 2 can be adjusted. After adjusting the length of the stroke the cover 11 is fixed in a suitable manner. Thus, for example, the cover 11 can consist of a synthetic material and, in such case, the cover 11 can be suitably welded to the rim of the housing 4 in order to thereby fix the length of the armature stroke. A suitable abutment member 6 for limiting the stroke of the armature 2 can also be attached to the cover 11. A mounting socket or base 5 is moreover formed directly at the lower part of the housing 4, as seen for example in FIG. 3. A component 7 formed of insulating material and carrying electrical connectors or leads 13 is also embedded in the synthetic housing 4. These connectors or leads 13 are thus directly embedded in a lateral direction in the housing 4 of synthetic material. In addition, the guide 12 for the actuating plunger 8, which cooperates with the armature 2, is also directly embedded in the housing 4. Furthermore, the guide 9 for the armature 2 is directly formed in the plastic housing 4.

When the housing cover 11 on the housing 4 is pressure-tightly joined thereto, for example by welding, the armature chamber 10 can be filled with a suitable damping liquid, such as oil, so that when the armature is actuated, mechanical damping of the armature movement is achieved due to displacement of the damping liquid through the gap located between the armature 2 and the armature guide 9.

An actuating magnet can be constructed in accordance with my invention very inexpensively and economically in a single operation by injection molding, casting or extruding with a single tool a housing of synthetic plastic material around the core, coil and armature components of the magnet. Due to the fact that the magnet of my invention is thus surrounded on all sides by insulating synthetic plastic material, it meets virtually all specifications as to safety. The electrical plug connections, the mounting socket or base and the mounting or securing elements can be directly cast on the housing or formed thereon. The housing of synthetic material, moreover, ensures that the core and the coil as Well as the other components of the magnet are exactly fixed with respect to one another, and afiords good heat dissipation which can be further improved by suitable shaping of the outer surfaces of the housing.

I claim:

1. A.-C. electromagnetic actuator comprising a magnet core formed of laminate plates, an excitation coil mounted on said magnet core and having electrical connector elements electrically connected thereto, a housing formed of synthetic material, said core and said coil being embedded with said electrical connector elements in said housing, said housing having an inner wall surface defining a pressure-tight armature chamber within said housing, and an armature displaceable axially Within said coil, said armature being completely enclosed in said chamber, said inner wall surface having guide means directly formed thereon for guiding said armature.

2. Electromagnetic actuator according to claim 1, including an actuating plunger cooperating with said armature, and guide means for said plunger, said plunger guide means being also directly formed on the inner wall surface of said housing of synthetic material.

3. Electromagnetic actuator according to claim 1, including an abutment member mounted on the wall of said housing surrounding said armature for limiting the displacement of said armature.

4. Electromagnetic actuator according to claim 3, including means for adjusting said abutment member so as to alter the displacement limit of said armature.

5. Electromagnetic actuator according to claim 1, wherein said synthetic material is selected from the group consisting of reinforced polyamides, non-reinforced polyamides, and epoxy resins.

References Cited UNITED STATES PATENTS 2,975,340 3/1961 Jencks et al. 335251 3,082,359 3/1963 Mangiafico et al. 335-260X 3,166,692 1/1965 Forrester et al. 335251 3,249,823 5/1966 Beardow 335258 3,331,042 7/1967 Erickson et al. 335262X GEORGE HARRIS, Primary Examiner US Cl. XR. 

